Bioactive Glass Composites Research Articles

A new approach to overcome cytotoxic effects of Cu by delivering dual therapeutic ions (Sr, Cu)

IntroductionThe incorporation of trace elements such as strontium (Sr) and copper (Cu) in the composition of mesoporous bioactive glass (MBG) is widely known to enhance its biological functionality for bone tissue regeneration MethodsTwo MBG powders with the composition 80SiO2-11CaO-5P2O5-XCuO/SrO, one doped with 4mol.% of CuO, the second with 4mol.% of SrO were blended in the weight ratios of Cu-MBG: Sr-MBG; 100:0, 70: 30, 50: 50, 30: 70 and 0:100 aiming at minimizing Cu to minimize the cytotoxicity of Cu while preserving its antimicrobial activity. The synergistic effects of Sr and Cu ions on bioactivity, cytotoxicity, and antimicrobial activity were studied. ResultsTransmission electron microscopy (TEM) examination of Cu-MBG and Sr-MBG showed fringes related to the development of a mesoporous structure. The specific surface area values of the Cu-MBG and Sr-MBG powders were 287 and 349 m2/g, respectively. A characteristic compact layer consisting of particles with platelet-like morphology commonly associated with HAp crystals was confirmed after 7 days soaking in simulated body fluid (SBF). Mouse preosteoblast cells (MC3T3-E1) exhibited higher cell viability when exposed to a 1% w/v eluate from blended Cu-MBG powders compared to pure Cu-MBG. Notably, the Cu-MBG: Sr-MBG ratio of 30:70 exhibited cell viability of around 85% at this concentration. A higher cell viability (above 100%) towards MC3T3-E1 cells was observed for all powders when tested with the 0.1% w/v eluate. With progressive increase in the amount of Cu-MBG in the blended system the bacterial inhibitory effects were more pronounced. The Cu ions releases from Cu-MBG generate hydroxyl ions and increase the pH leading to disruption of the cellular membrane of microbes, resulting in enhanced antimicrobial activity. ConclusionThis newly developed blended system composed of Cu and Sr doped MBGs is expected to be more effective as bioactive filler in comparison to single ion doped MBGs for bone tissue engineering applications.

Role of in-situ electrical stimulation on early-stage mineralization and in-vitro osteogenesis of electroactive bioactive glass composites

Bioactive glass (BAG) has emerged as an effective bone graft substitute due to its diverse qualities of biocompatibility, bioactivity, osteoblast adhesion and enhanced revascularization. However, inferior osteogenic capacity of BAG compared to autologous bone grafts continues to limiting it's wide-spread clinical applications towards repairing of bone fractures and healing. In this study, we have fabricated BAG composites with 0.5 to 2 wt% bismuth ferrite (BF, a multiferroic material) with an aim to generate in-situ electrical charges pertinent to early-stage bone regeneration thus mimicking natural bone, which is a piezoelectric material. The fabricated BAG composites were characterised in terms of microstructures, phase analysis, remanent polarization, wettability and subsequently evaluated for in vitro cell proliferation and osteogenesis with and without magnetic field exposure (200 mT, 30 min./day). Pre-osteoblast cells from mice (MC3T3-E1) seeded on these composites exhibited excellent cell growth without any cytotoxicity, which is further supported by FITC/DAPI staining and a live/dead assay. The results of Alizarin Red S assay and increased levels of Alkaline Phosphatase (ALP) activity, at 21 days of culture, suggest that the BAG-BF composites promote in vitro osteogenic differentiation of pre-osteoblast cells. The enhanced osteogenesis of BAG-BF composites was also confirmed through qRT-PCR analysis, which showed rapid upregulation of osteoblastogenic specific genes namely RunX-2, Collagen-1, Bone Sialo Protein, and ALP after 21 days. Additionally, the osteogenic differentiation was assessed by the Western Blot technique, which revealed significantly higher band intensity of osteogenic markers in BAG-1.5 BF and BAG-2 BF composites than pure BAG. These findings clearly demonstrate that in-situ electrical stimulation and osteoconductive capacity of BF reinforced BAG composites have positive impact on osteoblast cell development, bone formation, and healing.

Determination of the Optimum Architecture of Additively Manufactured Magnetic Bioactive Glass Scaffolds for Bone Tissue Engineering and Drug-Delivery Applications.

For better bone regeneration, precise control over the architecture of the scaffolds is necessary. Because the shape of the pore may affect the bone regeneration, therefore, additive manufacturing has been used in this study to fabricate magnetic bioactive glass (MBG) scaffolds with three different architectures, namely, grid, gyroid, and Schwarz D surface with 15 × 15 × 15 mm3 dimensions and 70% porosity. These scaffolds have been fabricated using an in-house-developed material-extrusion-based additive manufacturing system. The composition of bioactive glass was selected as 45% SiO2, 20% Na2O, 23% CaO, 6% P2O5, 2.5% B2O3, 1% ZnO, 2% MgO, and 0.5% CaF2 (wt %), and additionally 0.4 wt % of iron carbide nanoparticles were incorporated. Afterward, MBG powder was mixed with a 25% (w/v) Pluronic F-127 solution to prepare a slurry for fabricating scaffolds at 23% relative humidity. The morphological characterization using microcomputed tomography revealed the appropriate pore size distribution and interconnectivity of the scaffolds. The compressive strengths of the fabricated grid, gyroid, and Schwarz D scaffolds were found to be 14.01 ± 1.01, 10.78 ± 1.5, and 12.57 ± 1.2 MPa, respectively. The in vitro study was done by immersing the MBG scaffolds in simulated body fluid for 1, 3, 7, and 14 days. Darcy's law, which describes the flow through porous media, was used to evaluate the permeability of the scaffolds. Furthermore, an anticancer drug (Mitomycin C) was loaded onto these scaffolds, wherein these scaffolds depicted good release behavior. Overall, gyroid-structured scaffolds were found to be the most suitable among the three scaffolds considered in this study for bone tissue engineering and drug-delivery applications.

PREPARATION AND ACELLULAR IN-VITRO BIOACTIVITY OF SOLID STATE SINTERED 45S5 BIOACTIVE CERAMICS USING BIO-WASTES AS ALTERNATIVE RESOURCES FOR BIOMEDICAL APPLICATIONS

In this research, rice husk ash (RHA) and eggshell ash (EGA) were used as biogenic materials for total replacement of pure quartz (SiO2) and calcium oxide (CaO) respectively in the traditional 45S5 bioactive glass composition by powder metallurgy route. Body formulation with nominal composition 45% RHA (SiO2), 24.5 EGA (CaO), 24.5% Na2O and 6% P2O5 was composed. The batch material was properly mixed with addition of 2% PVA (Polyvinyl alcohol) as binder and compacted at 70 MPa to produce compact samples of 40 x 20 mm. The samples were then allowed to dry in an ambient temperature followed by sintering at 1000°C for 2 h, then allowed to cool to room temperature. Selected samples were immersed inside prepared simulated body fluid (SBF – pH 7.4) at 37 °C for 5, 9, and 18h respectively. Physical, microstructure and phase evaluation were conducted to examine the developed bio-ceramic. The results showed the bio-waste based 45S5 bioceramic has bulk density and porosity of 1.02 g/cm3 and 62% respectively while deposits of carbonate-hydroxyapatite were found to increase with immersion period showing good bioactivity and affirm that the developed bio-waste based bioceramics are bioactive and can find suitable application bone repair.

Multifaceted biomedical applications of bismuth oxide-doped bioactive glass: Synthesis challenges, characterization and potential clinical implications

Herewith, the present work reports a facile synthesis method of Bi2O3 doped 70 SiO2.30CaO binary bioactive glass system termed as modified Bi-BG (acronymed as mBi-BG) that indicates successful incorporation of Bi3+ into the silicate glassy network, on prior complex formation of the precursor bismuth nitrate salt with acetyl acetone to address the rapid decomposition rate of precursor bismuth nitrate. The binary bioactive glass composition as above mentioned (70 SiO2.30CaO) is named as BG/Control. The synthesis methodology addresses inherent challenges encountered in traditional sol-gel derived bismuth oxide incorporated bioactive glass (Bi-BG) synthesis wherein yellow coloured bismuth oxide gets separated from the glassy network as confirmed by XRD phase analysis. Next, mBi-BG (modified Bi-BG) was synthesized via modifying the sol gel method by introducing a chelating agent acetyl acetone to stabilize the precursor Bi (NO3)3 salt, and was characterized using XRD, FTIR, FESEM-EDX. TG-DSC and BET isotherm. In vitro bioactivity studies illustrate the formation of hydroxyapatite crystals on mBi-BG surface indicating its potential for bone repair and regeneration. Additionally, mBi-BG exhibits significant effect against Staphylococcus aureus (gram-positive) bacterial strain, highlighting its utility in preventing bacterial infections at surgical sites. Radiographic imaging of mBi-BG reveals excellent radiopacity comparable to human bone, rendering it suitable for image-guided surgeries and fluoroscopic procedures. In summary, mBi-BG emerges as a versatile biomaterial with enhanced bioactivity, antibacterial efficacy and radiopacity, thereby offering novel avenues in medical treatment modalities and patient care.

Quantitative study of early-stage transient bacterial adhesion to bioactive glass and glass ceramics: atomic force microscopic observations

Antimicrobial potential of bioactive glass (BAG) makes it promising for implant applications, specifically overcoming the toxicity concerns associated with traditional antibacterial nanoparticles. The 58S composition of BAG (with high Ca and absence of Na) has been known to exhibit excellent bioactivity and antibacterial behaviour, but the mechanisms behind have not been investigated in detail. In this pioneering study, we are using Atomic Force Microscopy (AFM) to gain insights into 58S BAG’s adhesive interactions with planktonic cells of both gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria; along with the impact of crystallinity on antibacterial properties. We have recorded greater bacterial inhibition by amorphous BAG compared to semi-crystalline glass–ceramics and stronger effect against gram-negative bacteria via conventional long-term antibacterial tests. AFM force distance curves has illustrated substantial bonding between bacteria and BAG within the initial one second (observed at a gap of 250 ms) of contact, with multiple binding events. Further, stronger adhesion of BAG with E.coli (~ 6 nN) compared to S. aureus (~ 3 nN) has been found which can be attributed to more adhesive nano-domains (size effect) distributed uniformly on E.coli surface. This study has revealed direct evidence of impact of contact time and 58S BAG’s crystalline phase on bacterial adhesion and antimicrobial behaviour. Current study has successfully demonstrated the mode and mechanisms of initial bacterial adhesion with 58S BAG. The outcome can pave the way towards improving the designing of implant surfaces for a range of biomedical applications.

Electrophoretic Deposition of Bioactive Glass Coatings for Bone Implant Applications: A Review

This literature review deals with the electrophoretic deposition of bioactive glass coatings on metallic substrates to produce bone implants. Biocompatible metallic materials, such as titanium alloys or stainless steels, are commonly used to replace hard tissue functions because their mechanical properties are appropriate for load-bearing applications. However, metallic materials barely react in the body. They need a bioactive surface coating to trigger beneficial biological and chemical reactions in the physiological environment. Bioactive coatings aim to improve bone bonding, shorten the healing process after implantation, and extend the lifespan of the implant. Bioactive glasses, such as 45S5, 58S, S53P4, 13-93, or 70S30C, are amorphous materials made of a mixture of oxides that are accepted by the human body. They are used as coatings to improve the surface reactivity of metallic bone implants. Their high bioactivity in the physiological environment induces the formation of strong chemical bonding at the interface between the metallic implant and the surrounding bone tissue. Electrophoretic deposition is one of the most effective solutions to deposit uniform bioactive glass coatings at low temperatures. This article begins with a review of the different compositions of bioactive glasses described in the scientific literature for their ability to support hard tissue repair. The second part details the different stages of the bioactivity process occurring at the surface of bioactive glasses immersed in a physiological environment. Then, the mechanisms involved in the electrophoretic deposition of bioactive glass coatings on metallic bone implants are described. The last part of the article details the current developments in the process of improving the properties of bioactive glass coatings by adding biocompatible elements to the glassy structure.

Fe-doped 45S5 bioactive glass compositions impair the metabolic activity and proliferation of metastatic human breast cancer cells in vitro

Many kinds of human tumors, including breast carcinomas, frequently metastasize to the bone, making it prone to pathologic fractures. Surgical management of bone metastases ranges from the resection of metastases to bone repair. Current surgical methods for the repair of bone defects include the use of polymethyl methacrylate (PMMA)-based bone cements. A promising alternative material are bioactive glass (BG) particles that in addition to providing physical stability can also induce bone regeneration. Moreover, BGs doped with Fe2O3may also have a negative impact on tumor cells. Here, we tested the hypothesis that BGs can affect metastatic human breast cancer cells. To this end, we assessed the effects of different BG compositions with and without Fe2O3on metastatic human MDA-MB-231 breast cancer cellsin vitro. We found that all BGs tested impaired the viability and proliferation of breast cancer cells in a concentration-dependent manner. The anti-proliferative effects inversely correlated with BG particle size, and were in general less pronounced in mesenchymal stromal cells (MSCs) that served as a control. Moreover, Fe2O3-doped BGs were more potent inhibitors of tumor cell proliferation and metabolic activity than Fe2O3-free BG. Our data therefore indicate that BGs can affect human breast cancer cells more strongly than MSCs, and suggest that the presence of Fe2O3can potentiate anti-proliferative and anti-metabolic effects of BGs. Fe2O3-doped BGs thus have the potential to be used for the surgical management of metastatic bone lesions, and may in addition to their regenerative properties also allow the local control of bone metastases.

Osteogenic potency of dental stem cell-composite scaffolds in an animal cleft palate model

ObjectiveTo evaluate the osteogenic potency of stem cells isolated from human exfoliated deciduous teeth (SHED) in polycaprolactone with gelatin surface modification (PCL-GE) and poly (lactic-co-glycolic acid)-bioactive glass composite (PLGA-bioactive glass (BG)) scaffolds after implantation in a rat cleft model. MethodsCleft palate-like lesions were induced in Sprague-Dawley rats by extracting the right maxillary first molars and drilling the intact alveolar bone. Rats were then divided into five groups: Control, PCL-GE, PCL-GE-SHED, PLGA-BG, and PLGA-BG-SHED, and received corresponding composite scaffolds with/without SHED at the extraction site. Tissue samples were collected at 2, 3, and 6 months post-implantation (4 rats per group). Gross and histological analyses were conducted to assess osteoid or bone formation. Immunohistochemistry for osteocalcin and human mitochondria was performed to evaluate bone components and human stem cell viability in the tissue. ResultsBone tissue formation was observed in the PCL-GE and PLGA-BG groups compared to the control, where no bone formation occurred. PLGA-BG scaffolds demonstrated greater bone regeneration potential than PCL-GE over 2–6 months. Additionally, scaffolds with SHED accelerated bone formation compared to scaffolds alone. Osteocalcin expression was detected in all rats, and positive immunoreactivity for human mitochondria was observed in the regenerated bone tissue with PCL-GE-SHED and PLGA-BG-SHED. ConclusionPCL-GE and PLGA-BG composite scaffolds effectively repaired and regenerated bone tissue in rat cleft palate defects. Moreover, scaffolds supplemented with SHED exhibited enhanced osteogenic potency. Clinical significancePCL-GE and PLGA-BG scaffolds, augmented with SHED, emerge as promising biomaterial candidates for addressing cleft repair and advancing bone tissue engineering endeavors.

Bioactive Glass for Applications in Implants: A Review

AbstractTraditional metallic biomaterials including titanium and its alloys, stainless steel, cobalt‐chromium alloys, magnesium alloys are gold standards for load bearing hard tissue applications, because of adequate mechanical properties such as elastic modulus, ductility and strength for long term support and stability. However, metallic implants suffer from poor osteointegration and early degradation in host body, owing to an array of factors which include stress shieling effect, corrosion, metal toxicity, microbial contamination and low bioactivity. Therefore, to improve integration of implants with host tissue and overall mechanical and biological functions, metallic implants are coated with bioactive glasses (BG). BG are one of the most promising implant coating materials used for bone repair and reconstruction, mainly because of excellent angiogenic, osteoconductive, osteoinductive, corrosion resistance, resorbability, biocompatibility, bioactivity and anti‐microbial properties. Various BG compositions are employed for diverse biomedical applications ranging from wound healing, bone formation, corrosion resistance, drug delivery to scaffolds in tissue engineering and different methods are used for coating BG on implants to enhance stability and bond strength between implant and coating. This narrative review gives a detailed overview on metallic implants, issues of metal alloys when used in implants and how metallic implants are improved by various BG compositions and coating methods. This review provides an updated information on advantages of different BG compositions in implants fabrication in order to address challenges and tailor mechanical and biological properties of implants for future applications.

Gelatin Methacryloyl (GelMA) - 45S5 Bioactive Glass (BG) Composites for Bone Tissue Engineering: 3D Extrusion Printability and Cytocompatibility Assessment Using Human Osteoblasts.

3D extrusion printing has been widely investigated for low-volume production of complex-shaped scaffolds for tissue regeneration. Gelatin methacryloyl (GelMA) is used as a baseline material for the synthesis of biomaterial inks, often with organic/inorganic fillers, to obtain a balance between good printability and biophysical properties. The present study demonstrates how 45S5 bioactive glass (BG) addition and GelMA concentrations can be tailored to develop GelMA composite scaffolds with good printability and buildability. The experimental results suggest that 45S5 BG addition consistently decreases the compression stiffness, irrespective of GelMA concentration, albeit within 20% of the baseline scaffold (without 45S5 BG). The optimal addition of 2 wt % 45S5 BG in 7.5 wt % GelMA was demonstrated to provide the best combination of printability and buildability in the 3D extrusion printing route. The degradation decreases and the swelling kinetics increases with 45S5 BG addition, irrespective of GelMA concentration. Importantly, the dissolution in simulated body fluid over 3 weeks clearly promoted the nucleation and growth of crystalline calcium phosphate particles, indicating the potential of GelMA-45S5 BG to promote biomineralization. The cytocompatibility assessment using human osteoblasts could demonstrate uncompromised cell proliferation or osteogenic marker expression over 21 days in culture for 3D printable 7.5 wt % GelMA -2 wt % 45S5 BG scaffolds when compared to 7.5 wt % GelMA. The results thus encourage further investigations of the GelMA/45S5 BG composite system for bone tissue engineering applications.

In vitro and in vivo dissolution of biocompatible S59 glass scaffolds

Fabrication of porous tissue-engineering scaffolds from bioactive glasses (BAG) is complicated by the tendency of BAG compositions to crystallize in thermal treatments during scaffold manufacture. Here, experimental biocompatible glass S59 (SiO2 59.7 wt%, Na2O 25.5 wt%, CaO 11.0 wt%, P2O5 2.5 wt%, B2O3 1.3 wt%), known to be resistant to crystallization, was used in sintering of glass granules (300–500 µm) into porous scaffolds. The dissolution behavior of the scaffolds was then studied in vivo in rabbit femurs and under continuous flow conditions in vitro (14 days in vitro/56 days in vivo). The scaffolds were osteoconductive in vivo, as bone could grow into the scaffold structure. Still, the scaffolds could not induce sufficiently rapid bone ingrowth to replace the strength lost due to dissolution. The scaffolds lost their structure and strength as the scaffold necks dissolved. In vitro, S59 dissolved congruently throughout the 14-day experiments, resulting in only a slight reaction layer formation. Manufacturing BAG scaffolds from S59 that retain their amorphous structure was thus possible. The relatively rapid and stable dissolution of the scaffold implies that the glass S59 may have the potential to be used in composite implants providing initial strength and stable, predictable release of ions over longer exposure times.Graphical

Komposit Bioactive Glass Berbasis Silika Abu Ampas Tebu dan Gum Mimba Menstimulasi Proses Remineralisasi Permukaan Gigi

Dentin hypersensitivity results from exposed dentinal tubules. One of the treatments used is remineralization of dentin and cementum. Bioactive glass (BAG) is a material that can stimulate the remineralization process due to its silica content. Sugarcane bagasse contains high levels of silica and is used as a BAG material. Adding binders and emulsifiers to paste forms increases bonding and stability and makes application easier. Neem gum is a polysaccharide, has emulsifying properties, and can unite two or more ingredients with different properties, increasing the strength of the ingredients. The study aims to analyse the effect of neem gum and bioactive glass composites based on silica bagasse ash on tooth remineralisation. There were three research groups, namely control (BAG paste), treatment A (hyaluronic acid BAG paste) and treatment B (BAG paste, hyaluronic acid and neem gum). The injection paste was applied to the teeth [using cow teeth] on the mesial surface, then soaked in artificial saliva for six days and stored in an incubator at 370C. The remineralization process was observed by forming hydroxycarbonate apatite (HCA) on the tooth root surface using a scoring method based on the Scanning Electron Microscope (SEM) results. CA formation in the BAG, hyaluronic acid and neem gum composite group had a significantly (p<0.05) higher HCA formation score than the group without gum. The control group experienced a washout, so no HCA was formed. BAG composite paste with silica based on bagasse ash and neem gum stimulates the remineralization process marked by the formation of HCA on the tooth root surface.

Processing and cytocompatibility of Cu-doped and undoped fluoride-containing bioactive glasses

Sintered or additive-manufactured bioactive glass (BG) scaffolds are highly interesting for bone replacement applications. However, crystallization often limits the high-temperature processability of bioactive glasses (BGs). Thus, the BG composition must combine high bioactivity and processability. In this study, three BGs with nominal molar (%) compositions 54.6SiO2-1.7P2O3-22.1CaO-6.0Na2O-7.9K2O-7.7MgO (13–93), 44.8SiO2-2.5P2O3-36.5CaO-6.6Na2O-6.6K2O-3.0CaF2 (F3) and 44.8SiO2-2.5P2O3-35.5CaO-6.6Na2O-6.6K2O-3.0CaF2-1.0CuO (F3–Cu) were investigated. The dissolution and ion release kinetics were investigated on milled glass powder and crystallized particles (500–600 μm). All glasses showed the precipitation of hydroxyapatite (HAp) crystals after 7 days of immersion in simulated body fluid. No significant differences in ion release from glass and crystalline samples were detected. The influence of surface roughness on cytocompatibility and growth of pre-osteoblast cells (MC3T3-E1) was investigated on sintered and polished BG pellets. Results showed that sintered BG pellets were cytocompatible, and cells were seen to be well attached and spread on the surface after 5 days of incubation. The results showed an inverse relation of cell viability with the surface roughness of pellets, and cells were seen to attach and spread along the direction of scratches.

A comparative analysis of the cytocompatibility, protein adsorption, osteogenic and angiogenic properties of the 45S5- and S53P4-bioactive glass compositions

Despite their long history of application in orthopedics, the osteogenic and angiogenic properties as well as the cytocompatibility and protein adsorption of the 45S5- (in wt%: 45.0 SiO2, 24.5 Na2O, 24.5 CaO, 6.0 P2O5) and S53P4- (in wt%: 53.0 SiO2, 23.0 Na2O, 20.0 CaO, 4.0 P2O5) bioactive glass (BG) compositions have not yet been directly compared in one and the same experimental setting. In this study, the influence of morphologically equal granules of both BGs on proliferation, viability, osteogenic differentiation and angiogenic response of human bone-marrow-derived mesenchymal stromal cells (BMSCs) was assessed. Furthermore, their impact on vascular tube formation and adsorption of relevant proteins was evaluated. Both BGs showed excellent cytocompatibility and stimulated osteogenic differentiation of BMSCs. The 45S5-BG showed enhanced stimulation of bone morphogenic protein 2 (BMP2) gene expression and protein production compared to S53P4-BG. While gene expression and protein production of vascular endothelial growth factor (VEGF) were stimulated, both BGs had only limited influence on tubular network formation. 45S5-BG adsorbed a higher portion of proteins, namely BMP2 and VEGF, on its surface. In conclusion, both BGs show favorable properties with slight advantages for 45S5-BG. Since protein adsorption on BG surfaces is important for their biological performance, the composition of the proteome formed by osteogenic cells cultured on BGs should be analyzed in order to gain a deeper understanding of the mechanisms that are responsible for BG-mediated stimulation of osteogenic differentiation.

Influence of the Addition of Zinc, Strontium, or Magnesium Oxides to the Bioglass 45S5 Network on Electrical Behavior.

45S5 Bioglass has been widely used in regenerative medicine due to its ability to dissolve when inserted into the body. Its typically amorphous structure allows for an ideal dissolution rate for the formation of the hydroxyapatite layer, which is important for the development of new bone. This bioactive capacity can also be controlled by adding other oxides (e.g., SrO, ZnO, and MgO) to the 45S5 Bioglass network or by storing electrical charge. Ions such as zinc, magnesium, and strontium allow for specific biological responses to be added, such as antibacterial action and the ability to increase the rate of osteoblast proliferation. The charge storage capacity allows for a higher rate of bioactivity to be achieved, allowing for faster attachment to the host bone, decreasing the patient's recovery time. Therefore, it is necessary to understand the variation in the structure of the bioglass with regard to the amount of non-bridging oxygens (NBOs), which is important for the bioactivity rate not to be compromised, and also its influence on the electrical behavior relevant to its potential as electrical charge storage. Thus, several bioactive glass compositions were synthesized based on the 45S5 Bioglass formulation with the addition of various concentrations (0.25, 0.5, 1, and 2, mol%) of zinc, strontium, or magnesium oxides. The influence of the insertion of these oxides on the network was evaluated by studying the amount of NBOs using Raman spectroscopy and their implication on the electrical behavior. Electrical characterization was performed in ac (alternating current) and dc (direct current) regimes.

Osteogenic-angiogenic coupled response of cobalt-containing mesoporous bioactive glasses in vivo

The incorporation of cobalt ions into the composition of bioactive glasses has emerged as a strategy of interest for bone regeneration purposes. In the present work, we have designed a set of bioactive mesoporous glasses SiO2-CaO-P2O5-CoO (Co-MBGs) with different amounts of cobalt. The physicochemical changes introduced by the Co2+ ion, the in vitro effects of Co-MBGs on preosteoblasts and endothelial cells and their in vivo behaviour using them as bone grafts in a sheep model were studied. The results show that Co2+ ions neither destroy mesoporous ordering nor inhibit in vitro bioactive behaviour, exerting a dual role as network former and modifier for CoO concentrations above 3 % mol. On the other hand, the activity of Co-MBGs on MC3T3-E1 preosteoblasts and HUVEC vascular endothelial cells is dependent on the concentration of CoO present in the glass. For low Co-MBGs concentrations (1mg/ml) cell viability is not affected, while the expression of osteogenic (ALP, RUNX2 and OC) and angiogenic (VEGF) genes is stimulated. For Co-MBGs concentration of 5 mg/ml, cell viability decreases as a function of the CoO content. In vivo studies show that the incorporation of Co2+ ions to the MBGs improves the bone regeneration activity of these materials, despite the deleterious effect that this ion has on bone-forming cells for any of the Co-MBG compositions studied. This contradictory effect is explained by the marked increase in angiogenesis that takes place inside the bone defect, leading to an angiogenesis-osteogenesis coupling that compensates for the partial decrease in osteoblast cells. Statement of significanceThe development of new bone grafts implies to address the need for osteogenesis-angiogenesis coupling that allows bone regeneration with viable tissue in the long term. In this sense the incorporation of cobalt ions into the composition of bioactive glasses has emerged as a strategy of great interest in this field. Due to the potential cytotoxic effect of cobalt ions, there is an important controversy regarding the suitability of their incorporation in bone grafts. In this work, we address this controversy after the implantation of cobalt-doped mesoporous bioactive glasses in a sheep model. The incorporation of cobalt ions in bioactive glasses improves the bone regeneration ability of these bone grafts, due to enhancement of the angiogenesis-osteogenesis coupling.

A COMPARATIVE STUDY OF THREE DIFFERENT BIOACTIVE GLASS SCAFFOLDS TAILORED FOR CARTILAGE TISSUE ENGINEERING

The regenerative capacity of hyaline cartilage is greatly limited. To prevent the onset of osteoarthritis, cartilage defects have to be properly treated. Cartilage, tissue engineered by mean of bioactive glass (BG) scaffolds presents a promising approach. Until now, conventional BGs have been used mostly for bone regeneration, as they are able to form a hydroxyapatite (HA) layer and are therefore, less suited for cartilage reconstruction. The aim of this study is to compare two BGs based on a novel BG composition tailored specifically for cartilage (CAR12N) and patented by us with conventional BG (BG1393) with a similar topology. The highly porous scaffolds consisting of 100% BG (CAR12N, CAR12N with low Ca2+/Mg2+ and BG1393) were characterized and dynamically seeded with primary porcine articular chondrocytes (pACs) or primary human mesenchymal stem cells (hMSCs) for up to 21 days. Subsequently, cell viability, DNA and glycosaminoglycan contents, cartilage-specific gene and protein expression were evaluated. The manufacturing process led to a comparable high (over 80%) porosity in all scaffold variants. Ion release and pH profiles confirmed bioactivity for them. After both, 7 and 21 days, more than 60% of the total surfaces of all three glass scaffold variants was densely colonized by cells with a vitality rate of more than 80%. The GAG content was significantly higher in BG1393 colonized with pACs. In general, the GAG content was higher in pAC colonized scaffolds in comparison to those seeded with hMSCs. The gene expression of cartilage-specific collagen type II, aggrecan, SOX9 and FOXO1 could be detected in all scaffold variants, irrespectively whether seeded with pACs or hMSCs. Cartilage-specific ECM components could also be detected at the protein level. In conclusion, all three BGs allow the maintenance of the chondrogenic phenotype or chondrogenic differentiation of hMSCs and thus, they present a high potential for cartilage regeneration.

Advances in Dental Materials: Bioactive Glass and Ceramic Composites: A Review

In recent times, there have been notable advancements in dental materials, with particular emphasis on the progress made in the development of bioactive glass and ceramic composites. The unique capacity of bioactive glass to promote bone regeneration and repair has garnered significant attention. This has led to its widespread use in the field. The utilisation of ceramic composites as dental materials has exhibited favourable outcomes owing to their superior strength, biocompatibility, and aesthetic. The present review article provides an overview of the latest developments in bioactive glass and ceramic composites, encompassing their characteristics, manufacturing techniques, and employment in the field of dentistry. The present study will concentrate on the application of bioactive glass in the fields of restorative dentistry, bone augmentation interventions, and endodontic treatment. The utilisation of ceramic composites in implant dentistry will be examined, along with their prospective implementation in other dental contexts. This review aims to elucidate the difficulties that are linked with the utilisation of said materials, including their fragility and the requirement for meticulous handling, in addition to plausible remedies for mitigating these difficulties. The current review article illustrates the advancements in bioactive glass and ceramic composites possess the capacity to considerably enhance the results of diverse dental procedures, thereby furnishing patients with restorations that are more enduring, visually appealing, and biocompatible.

The effect of copper addition on strontium-containing silicate-based sol-gel bioactive glass for tissue regeneration

Previous studies on bioactive glasses (BGs) have reported the therapeutic potential of either strontium (Sr2+) or copper (Cu2+) ions as dopants. This study incorporates both dopants into a novel BG composition for soft tissue attachment. The X-ray diffraction (XRD) patterns showed the presence of multiple crystalline phases, including copper oxide (CuO). Thermal analysis revealed the glass transition temperatures (Tg) ranged from 543 to 561 °C and decreased as Cu2+ concentrations increased. Raman spectroscopy showed the glass structure contained predominantly Q2 and Q3 species, while particle size and surface area were between 1.1–2.5 µm and 8–15 m2/g, respectively. No Cu2+ ions were released from the glass structure after 1000 h of incubation in deionized (DI) water. Agar diffusion testing against S. aureus found that each glass possessed antibacterial properties, with 4 mol% containing Cu-BG presenting the most significant inhibition zones at 3.1 ± 0.1 mm over the 7-day incubation time.